1. Field of the Invention
The present invention relates to an electronic camera which has a function of automatically setting a gray-scale transformation characteristic depending on the type of an image.
2. Description of the Related Art
An electronic camera of a type, which obtains an image with image sensors, performs gray-scale transformation on an image outputted from the image sensors. Performing this gray-scale transformation makes it possible to offset the characteristics (inclination) of the image sensor, and to adjust the image according to the display characteristics of a monitor as a general display device. It also enables transformation of an undesirable image to a desirable image.
The electronic camera, however, may perform an unsuitable gray-scale transformation on particular images. In some case, when the gray-scale transformation is performed on a subject image having a wide range of intensity, for example, a dark portion of the image may appear inky black or a bright portion of the image may appear stark white. For other cases, when the gray-scale transformation is performed on a subject image having a small range of intensity, the image may lose distinctiveness in brightness.
Japanese Unexamined Patent Application Publication No. 2001-54014 discloses a technique for determining the type of a subject from an output of a split photometric sensor to automatically set an optimal gray-scale transformation characteristic in accordance with the type of the subject. Even by this technique, however, there are images of some subject (namely, subject with luminescent or black spots) on which the gray-scale transformation cannot be executed with a user-satisfying level.